The presence of metals in fluid streams is deleterious for many uses. For example, governmental regulations now require the marketing of gasolines having at most 0.05 grams of lead per gallon in order to prevent poisoning of noble metal containing catalytic mufflers installed on internal combustion engines. Although non-leaded gasolines may be produced at petroleum refineries with adequately low lead level to meet the legal requirement, occasionally the gasolines will absorb small but significant amounts of lead compounds from storage, or by inadvertent contamination during transportation in lead contaminated tanks or pipelines to exceed this limit.
In a like manner, metals such as lead and copper may be found in hydrocarbon distillate fuels owing to contamination during shipping or storage. Those metals in concentrations above a few parts per million tend to promote deposit of solids, cause corrosion and otherwise accelerate maintenance problems of the engines, turbines and the like in which the fuel is combusted. Also, in the refining of petroleum, metals such as lead, nickel and vanadium are deleterious to many catalytic processes particularly those in which hydrogen is consumed or generated. Often in such processes the liquid or vaporized feed is first passed through a "guard bed" of metals adsorbent, in order to protect the catalyst. However, with heavy contamination the guard bed may unexpectedly become exhausted. Accordingly, it would be highly desirable to be able to continuously monitor fluid streams to detect metals contamination at an early time, in order to be able to control the fluid flow and prevent or at least minimize deleterious consequences thereof.